Communication system receivers commonly utilize automatic gain control (AGC) techniques to control gain in one or more receiver stages. For example, a typical receiver includes front end circuitry and baseband circuitry, each of which may have one or more separate AGC circuits associated therewith. Such AGC circuits are commonly utilized to adjust the gain of one or more amplifiers in a given signal path so as to maintain desired signal level ranges for the path in the presence of variations in received signal strength.
An example of a known AGC circuit is described in U.S. Pat. No. 6,181,201, issued Jan. 30, 2001 to Peter J. Black and entitled “Automatic Gain Control Circuit for Controlling Multiple Variable Gain Amplifier Stages While Estimating Signal Power,” which is incorporated by reference herein.
It is also known that certain amplifiers can be configured with an adjustable bias current. An example of such an arrangement is described in U.S. Pat. No. 6,175,279, issued Jan. 16, 2001 to Steven C. Ciccarelli et al. and entitled “Amplifier With Adjustable Bias Current,” which is incorporated by reference herein.
A drawback of existing communication system receivers is the amount of power consumed by the receiver baseband circuitry. In a typical receiver, amplifiers in the baseband circuitry are biased at a substantially constant level, resulting in a certain amount of power consumption. Information that may be known regarding signal strength is generally not utilized to adjust the bias level in the baseband circuitry, with the result that this circuitry may consume an unduly high amount of power under certain operating conditions.
A need therefore exists for improved techniques for controlling bias in baseband circuitry of a communication system receiver or other device.